VaDeR asked:


i heard never to buy the viagra knock offs but i did and im scared of using it.. they still say they are sildenafil citrate but i don’t know if they’re any good.. they said that sum don’t even get u an erection and sum are so bad that they mess up ur heart is it true?

Martin asked:


How was the compound Sildenafil Citrate (Viagra) found and what was it extracted from?
Are Tadalafil Citrate (Cialis) and Vardenafil HCL (Levitra) extracted from the same plant source as Viagra is?

Daniel R asked:


As a bonus for my Organic Class, I am looking for a detailed mechanism for the synthesis of Benzene to Sildenafil Citrate (Viagra) or the synthesis of Benzene to tadalafil (Cialis). I am trying to find a link to the detailed mechanism, or at least one that is very close.